Being that you're mechanically qualified, I wouldn't hesitate to tackle this project. Working alone after work and on the weekends I finished my rebuild in a few months working here and there. Like westend mentioned, one of the challenges is keeping the trailer out of the weather. I needed to replace the roof and the rear half walls and floor, so I wresteled with tarps quite often during that time.
Because I was doing the roof as well I worked from the outside in. When doing the walls I was able to peel the siding away, rebuild the walls, and then reattach the siding. I was also able to reuse all of the siding after finessing (hammering) it back into shape. This may not be relevant to you if you're going with a new structure.
It sounds like you're planning to demo and start from the bare frame which may actually be easier than fixing the issues. I would also recommend retaining the existing siding if at all possible depending on the dimensions of the rebuild.
Good luck with he project and keep us posted on progress. I love seeing the progress of these rebuilds and the ideas people come up with.
